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package org.hsqldb.trigger;

import org.hsqldb.HsqlException;

// fredt@users 20030727 - signature altered to support update triggers
// fredt@users 20190327 - moved to own package
/*

Contents of row1[] and row2[] in each type of trigger.

AFTER INSERT
 - row1[] contains single String object = "Statement-level".

AFTER UPDATE
 - row1[] contains single String object = "Statement-level".

AFTER DELETE
 - row1[] contains single String object = "Statement-level".

BEFORE INSERT FOR EACH ROW
 - row2[] contains data about to be inserted and this can
be modified within the trigger such that modified data gets written to the
database.

AFTER INSERT FOR EACH ROW
 - row2[] contains data just inserted into the table.

BEFORE UPDATE FOR EACH ROW
 - row1[] contains currently stored data and not the data that is about to be
updated.

 - row2[] contains the data that is about to be updated.

AFTER UPDATE FOR EACH ROW
 - row1[] contains old stored data.
 - row2[] contains the new data.

BEFORE DELETE FOR EACH ROW
 - row1[] contains row data about to be deleted.

AFTER DELETE FOR EACH ROW
 - row1[] contains row data that has been deleted.

List compiled by Andrew Knight (quozzbat@users)
*/

The interface an HSQLDB TRIGGER must implement. The user-supplied class that
implements this must have a default constructor.
Author:
Peter Hudson (peterhudson@users dot sourceforge.net)
Version:
1.9.0
Since:
1.7.0/**
 * The interface an HSQLDB TRIGGER must implement. The user-supplied class that
 * implements this must have a default constructor.
 *
 * @author Peter Hudson (peterhudson@users dot sourceforge.net)
 * @version 1.9.0
 * @since 1.7.0
 */
public interface Trigger {

    // type of trigger
    int INSERT_AFTER      = 0;
    int DELETE_AFTER      = 1;
    int UPDATE_AFTER      = 2;
    int INSERT_AFTER_ROW  = 3;
    int DELETE_AFTER_ROW  = 4;
    int UPDATE_AFTER_ROW  = 5;
    int INSERT_BEFORE_ROW = 6;
    int DELETE_BEFORE_ROW = 7;
    int UPDATE_BEFORE_ROW = 8;

    
The method invoked upon each triggered action.
 type contains the integer index id for trigger type, e.g.
TriggerDef.INSERT_AFTER
 For all triggers defined as default FOR EACH STATEMENT both
 oldRow and newRow are null.
 For triggers defined as FOR EACH ROW, the following will apply:
 When UPDATE triggers are fired, oldRow contains the existing values
of the table row and newRow contains the new values.
 For INSERT triggers, oldRow is null and newRow contains the table row
to be inserted. For DELETE triggers, newRow is null and oldRow contains
the table row to be deleted.
 For error conditions, users can construct an HsqlException using one
of the static methods of org.hsqldb.error.Error with a predefined
SQL State from org.hsqldb.error.ErrorCode.
Params:
type – the type as one of the int values defined in the interface
trigName – the name of the trigger
tabName – the name of the table upon which the triggered action is
  occurring
oldRow – the old row
newRow – the new row
Throws:
HsqlException – the preferred type of exception thrown by the method/**
     * The method invoked upon each triggered action.
     *
     * <p> type contains the integer index id for trigger type, e.g.
     * TriggerDef.INSERT_AFTER
     *
     * <p> For all triggers defined as default FOR EACH STATEMENT both
     *  oldRow and newRow are null.
     *
     * <p> For triggers defined as FOR EACH ROW, the following will apply:
     *
     * <p> When UPDATE triggers are fired, oldRow contains the existing values
     * of the table row and newRow contains the new values.
     *
     * <p> For INSERT triggers, oldRow is null and newRow contains the table row
     * to be inserted. For DELETE triggers, newRow is null and oldRow contains
     * the table row to be deleted.
     *
     * <p> For error conditions, users can construct an HsqlException using one
     * of the static methods of org.hsqldb.error.Error with a predefined
     * SQL State from org.hsqldb.error.ErrorCode.
     *
     * @param type the type as one of the int values defined in the interface
     * @param trigName the name of the trigger
     * @param tabName the name of the table upon which the triggered action is
     *   occurring
     * @param oldRow the old row
     * @param newRow the new row
     * @throws HsqlException the preferred type of exception thrown by the method
     */
    void fire(int type, String trigName, String tabName, Object[] oldRow,
              Object[] newRow);
}